[PATCH v3 7/9] iommu/arm-smmu-v3: Link domains and devices

Jean-Philippe Brucker
2019-04-17T18:24:46Z

When removing a mapping from a domain, we need to send an invalidation to
all devices that might have stored it in their Address Translation Cache
(ATC). In addition when updating the context descriptor of a live domain,
we'll need to send invalidations for all devices attached to it.

Maintain a list of devices in each domain, protected by a spinlock. It is
updated every time we attach or detach devices to and from domains.

It needs to be a spinlock because we'll invalidate ATC entries from
within hardirq-safe contexts, but it may be possible to relax the read
side with RCU later.

Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker-5wv7dgnIgG8@public.gmane.org>
---
drivers/iommu/arm-smmu-v3.c | 21 ++++++++++++++++++++-
1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 7b425483f4b6..3e7198ee9530 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -581,6 +581,7 @@ struct arm_smmu_device {
struct arm_smmu_master {
struct arm_smmu_device *smmu;
struct arm_smmu_domain *domain;
+ struct list_head domain_head;
u32 *sids;
unsigned int num_sids;
};
@@ -607,6 +608,9 @@ struct arm_smmu_domain {
};

struct iommu_domain domain;
+
+ struct list_head devices;
+ spinlock_t devices_lock;
};

struct arm_smmu_option_prop {
@@ -1504,6 +1508,9 @@ static struct iommu_domain *arm_smmu_domain_alloc(unsigned type)
}

mutex_init(&smmu_domain->init_mutex);
+ INIT_LIST_HEAD(&smmu_domain->devices);
+ spin_lock_init(&smmu_domain->devices_lock);
+
return &smmu_domain->domain;
}

@@ -1721,9 +1728,16 @@ static void arm_smmu_install_ste_for_dev(struct arm_smmu_master *master)

static void arm_smmu_detach_dev(struct arm_smmu_master *master)
{
- if (!master->domain)
+ unsigned long flags;
+ struct arm_smmu_domain *smmu_domain = master->domain;
+
+ if (!smmu_domain)
return;

+ spin_lock_irqsave(&smmu_domain->devices_lock, flags);
+ list_del(&master->domain_head);
+ spin_unlock_irqrestore(&smmu_domain->devices_lock, flags);
+
master->domain = NULL;
arm_smmu_install_ste_for_dev(master);
}
@@ -1731,6 +1745,7 @@ static void arm_smmu_detach_dev(struct arm_smmu_master *master)
static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
{
int ret = 0;
+ unsigned long flags;
struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
struct arm_smmu_device *smmu;
struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
@@ -1764,6 +1779,10 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)

master->domain = smmu_domain;

+ spin_lock_irqsave(&smmu_domain->devices_lock, flags);
+ list_add(&master->domain_head, &smmu_domain->devices);
+ spin_unlock_irqrestore(&smmu_domain->devices_lock, flags);
+
if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1)
arm_smmu_write_ctx_desc(smmu, &smmu_domain->s1_cfg);

--
2.21.0